It seems as if Microsoft might be punting out its next desktop OS for free, at least for some folks.

The word from "WZOR" (a well-known and respected Microsoft leaker) via T3 is that those who have Windows 8.1 will be granted a special offer to grab Windows 9 in some cases for no cost. Apparently, folks who bought the retail version of Windows 8 (or have an OEM version) will be looking at a £12 upgrade fee for Windows 9. So either way, you might end up paying nothing or very little for the updated OS.

Microsoft is also putting together some sort of major incentive to persuade those still using Windows XP to finally upgrade to a modern version of the OS (which really needs to happen given that support for XP has long since fallen by the wayside).

All these rumoured moves make sense, given the sluggish adoption rate for Windows 8: Redmond does indeed need to persuade XP'ers, and particularly businesses still running XP, that they need to make the leap. And it also seems fair to reward those who've adopted Windows 8, and not make folks pay twice in relatively quick succession for Win 8 and then Win 9 (seeing as the latter, codenamed Threshold, has kind of been rushed out to deal with the problems of the former).

Windows 9 is expected to be much more desktop (mouse and keyboard) user friendly, and will ditch the Charms bar, bring back a traditional Start menu, and even allow things like running modern (new-style) apps in windowed mode (gasp).

Windows 9 is expected to be unveiled at the end of September, and is also likely to come with Cortana (Redmond's voice assistant from Windows Phone) integrated in some form, if not heavily.

WZOR also claimed that the enterprise version of Windows 9 will do away with the "Metro" (new-style) side of the OS completely.

Of course, this isn't the first time we've heard whispers on the grapevine about Windows 9 coming gratis. Indeed, earlier this month, Mary Jo Foley claimed that the OS would be offered to Windows XP, Vista and Windows 7 users for nothing.